Article

PURPOSE: To investigate the cross-training effect, induced on ankle dorsiflexors
(AD) by unilateral strength-training of the contralateral muscles, as transfer of
peak torque (PT) and muscle work (MW) and their relative contributions to muscle
performance. METHODS: Thirty healthy volunteers were randomly assigned to a
training or control group. The trained group sustained a 4-week maximal
isokinetic training of the stronger AD at 90 and 45 degrees /s.
At both angular
velocities, PT, MW and MW/PT ratio were measured from both legs at baseline and
after intervention (trained group) or no-intervention (controls). The
familiarization/learning-effect was calculated and subtracted by PT and MW
measures to obtain their net changes. RESULTS: Net PT increased in both legs
(untrained: +27.5% at 90 degrees /s and +17.9% at 45 degrees /s; trained: +15% at
90 degrees /s and +16.3% at 45 degrees /s). Similarly, net MW increased in both
the untrained (90 degrees /s: +29.6%; 45 degrees /s: +37%) and trained (90
degrees /s: +23.4%; 45 degrees /s: +18.3%) legs. PT and MW gains were larger in
the untrained than trained AD (p<0.0005), with MW improving more than PT at 45
degrees /s (p=0.04). The MW/PT ratio increased bilaterally only in the trained
group (p<0.05), depending on the angular velocity. CONCLUSIONS: The
cross-training effect occurred in AD muscles in terms of both PT and MW, with MW
adding valuable information to PT-analysis in describing muscle performance.
Moreover, the MW/PT ratio allowed estimating the contributions of these
parameters to muscle capability and may represent a novel index in isokinetic
testing. The greater improvements in the untrained than trained limb raises
interesting clinical implications in asymmetric conditions.
CI - Copyright (c) 2015 Elsevier B.V. All rights reserved.

Langue : ANGLAIS